Within laboratory environments, especially in the field of microbiology, the employment of a Bunsen burner is frequently linked to the preservation of a sterile atmosphere. The common perception is that the flame from the burner generates a convection current that pulls air upwards, thus removing dust and microbial pollutants from the workspace. However, a recent investigation carried out by a team from Providence College in Rhode Island questions this long-held belief.
As reported in Microbiology Spectrum, the research indicates that Petri dishes situated near an active Bunsen burner gathered comparable amounts of bacteria to those positioned near a non-active burner. The researchers, led by Kate DeVincent and her team, performed experiments by exposing Petri dishes to airborne bacteria with and without the burner’s presence. Their findings showed no statistically significant decrease in bacterial contamination within the supposed sterile area surrounding the flame.
The Setup and Results of the Study
The inquiry involved creating matching workstations, one with a lit Bunsen burner and the other without. Plates containing tryptic soy agar were set at an equal distance from the burner, left exposed, and subsequently incubated. Contrary to the long-standing belief in the effectiveness of the convection current theory that students are taught, the research noted no noticeable difference in the bacterial colony counts between plates adjacent to a lit burner and those near an unlit one.
While the commonly held notion suggested a protective air zone around the flame, the authors discovered no scientific proof endorsing its existence. Their results resonate with earlier doubts expressed in scientific writings, including a 1996 article that highlighted the lack of quantitative research on this matter.
Context and Wider Implications
This investigation is not an isolated occurrence. It recalls similar conclusions drawn in 1972 concerning the practice of flaming the mouths of test tubes, which was also found to be ineffective. In spite of such findings, conventional practices, including the usage of a Bunsen burner, remain extensively taught and implemented, likely due to the psychological comfort offered by a visible flame during laboratory activities.
The study advocates for alternative strategies to uphold aseptic conditions that are more economical, such as utilizing HEPA filters or still air boxes, particularly in settings with limited resources. The authors suggest a localized approach to evaluate the necessity of a burner by employing settle plate assays to gauge ambient contamination levels.
This research underscores the significance of evidence-based methodologies in laboratories, while also questioning established practices. It sheds light on the ongoing discussion between traditional techniques and contemporary evidence, encouraging educators and researchers to reassess the safety and effectiveness of their laboratory methods.